.rebackgroundimg {
    width: 100%;
    height: auto;

    background: url(../img/adminback.jpg) no-repeat;
    background-size: cover;

    box-sizing: border-box;
}

.rebackgroundimg1 {
    width: 100%;
    height: auto;

    background: url(../img/beijing2.jpg) no-repeat;
    background-size: cover;

    box-sizing: border-box;
}

.rebackgroundimg2 {
    width: 100%;
    height: auto;

    background: url(../img/beijing3.jpg) no-repeat;
    background-size: cover;

    box-sizing: border-box;
}